Multi-zone grinding and/or polishing sheet

ABSTRACT

The invention relates to grinding/polishing sheet, which comprises 2 or more annular grinding/polishing zones ( 1-5 ) separated by intermediate annular distancing zones ( 6 ). One or more of the grinding polishing zones ( 1-5 ) comprises one or more non-continuous areas, that are part of an annular structure forming channels ( 8 ) in radial direction. The grinding/polishing sheet can be placed on a rotatable grinding/polishing disc for manual, automatic or semiautomatic preparations of materialographic samples. The invention also relates to a method for preparations of materialographic samples.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a cover sheet for placing on arotatable grinding/polishing (treatment) disc for manual, automatic orsemiautomatic preparations of materialographic samples. The inventionalso relates to a method of performing preparation of a materialographicsample using one or more cover sheets.

2. The Prior Art

The preparation of materialographic samples, e.g., metallographic,petrographic and ceramographic samples, is usually performed by use of arotatable grinding/polishing disc covered with a grinding/polishingsheet. The preparation is normally performed in 3 or more steps, viz.one or more plane grinding steps, one or more fine grinding steps, andone or more polishing steps.

Traditional grinding sheets also designated cover sheets, contain anabrasive material incorporated into the surface adapted to be broughtinto contact with the sample to be treated. A very used type of coversheet consists of a paper or paper-like substrate onto which abrasiveparticles are adhered. The main drawback of this sheet type is, that ithas a very short lifetime and needs to be exchanged very often, whichrequires a lot of work.

Some of the cover sheets employed today are not in themselves abrasive,but serve as a substrate for an abrasive grinding/polishing agent, whichis sprayed or otherwise applied onto the surface of the cover sheet,either automatically or manually before or under the grinding/polishingprocess.

Cover sheets in the form of metal support plates covered with hardcoatings consisting of a composite material, e.g. of epoxy with hardparticles of one or more metals or ceramic particles embedded thereinare also well known. In the prior art, cf. e.g. DK 143096, such coatingsare moulded on or glued to a self-supporting rigid plate, e.g. in theform of mutually separated segments, where after the surface of thecoatings is straightened by turning and/or grinding. In this manner atool is formed, which can be mounted as grinding/polishing disc in agrinding/polishing apparatus.

WO 96/07508 publication discloses a similar cover sheet consisting of athin foil, which is relatively stiff and onto which a hard compositematerial has been applied through a stencil in a desired thickness andpattern.

When performing preparation of materialographic samples using prior artgrinding/polishing sheets as described above, the operator must in thefirst plan grinding step use a first cover sheet containing incorporatedabrasive particles in order to remove sufficient material relativelyfast to make the surface plan. Thereafter, for the fine grinding of thesamples, he may use a non-abrasive cover sheet together with an abrasivegrinding agent or he may use a cover sheet containing incorporatedabrasive particles with has a smaller size than the abrasive particlesin the first cover sheet. In case the cover sheets used for the finegrinding procedure is in the form of SiC paper with incorporatedabrasive particles, he will need to employ several fine grinding stepwith progressively finer grain sizes e.g. 2-4 fine grinding step, and ineach of these fine grinding step he need to use several sheets due toweak durability,. In the polishing step, he should replace the coversheet with a cover sheet adapted for polishing in combination with theuse of a polishing agent. If the sample should have a very fine polishedsurface e.g. an oxide polished surface, he will need to change the sheetonce more and replace it with a cover sheet adapted for performing anoxide polishing.

As it appears, the operation is very time-consuming, and it is veryexpensive to construct an apparatus, which automatically can propagatethe samples due to the many shifts of cover sheets. If the preparationis conducted manually, it is very time-consuming for the operator due tothe exchange of cover sheets or the operator may use several rotatablediscs, one for each sheet. Generally, it is an expensive solution to useseveral rotatable discs.

U.S. Pat. No. 959,054 describes a cover sheet containing abrasivematerial to one of its surfaces. The abrasive on the sheet is ofdifferent degree of fineness varying gradually and uniformly fromcoarser abrasive material at the centre, to finer abrasive material atthe outer edge.

When using this cover sheet, the article to be treated is placed againstthe sheet near its centre and gradually moved towards the outer edge.The main drawback of using this sheet is that the abrasive material isworn of as the grinding process is performed. Some of the largerabrasive particles worn out of the sheet from near its centre will beincorporated into the sheet or be grabbed by the smaller abrasiveparticles closer to its outer edge, and consequently, be an obstructionof a polishing of a sample, because these coarser particles will createunwanted grinding scratches in the sample. Generally, it is almostimpossible to control the grinding/polishing procedure because theabrasive materials after the procedure is initiated will be more or lessmixed op with each other. Another drawback is that the sheet mainly willbe worn in the annular centre portion of each abrasive zone, which meansthat it can only be used for a very short time before a heightdifference is created. Such height difference in the abrasive materialmay result in an uneven grinding and polishing of the samples, which ishighly unwanted. As a consequence of these many drawbacks of the coversheet described in U.S. Pat. No. 959,054, this sheet has never beencommercialised.

The objective of the present invention is to provide agrinding/polishing cover sheet, by which the drawbacks of the previouslyknown cover sheets are avoided.

It is particular an object of the invention to provide agrinding/polishing cover sheet by use of which, the numerous changes ofcover sheets during a process of preparation of a materialographicsample can be reduced or avoided, and particularly, it is an objectiveto provide a cover sheet by use of which two or more grinding/polishingsteps can be performed without any substantial risk of contaminatingabrasive materials from a first grinding/polishing step to a secondgrinding/polishing step under performing of this second step.

Another objective of the present invention is to provide agrinding/polishing cover sheet, which can be easily used without therisk of creating height differences in the surface of the sheet, whichmight result in creating the surface of a sample uneven.

Yet a further objective of the present invention is to provide a methodof grinding/polishing a sample in two or more steps using one singlecover sheet, by use of which method the risk of contaminating abrasivematerials from a first grinding/polishing step to a secondgrinding/polishing step under performing of this second step issubstantially eliminated.

SUMMARY OF THE INVENTION

It has been found that by use of the grinding/polishing (treatment)sheet according to the invention, abrasive material from a firstgrinding/polishing zone does not result in any substantial contaminationof a second grinding/polishing zone, in particular not when the secondgrinding/polishing zone is placed closer to the centre of the sheet thansaid first zone. The channels between the grinding/polishing zonescreate barriers between juxtaposed grinding/polishing zones, whichparticularly prevent the transportation of abrasive material to otherzones and in particular to other zones lying closer to the centre of thesheet than the zone where the abrasive material is placed orincorporated.

The grinding/polishing sheet according to the invention may in principlehave an unlimited number of annular concentric grinding/polishing zones.However, due to the size of the sheet, it is preferred that the numberof grinding/polishing zones is between 2 and 6. Mostly, it is preferredthat the sheet has 2, 3 or 4 grinding/polishing zones. The term annularzone also encompasses a zone with circular shape, which e.g. may beplaced in the centre of the grinding/polishing sheet.

The grinding/polishing sheet is to be understood as a carrier medium,which during operation is attached to a rotating disc with one of itssides. On the opposite side the grinding/polishing sheet has thegrinding/polishing zones attached. The side of grinding/polishing sheetwith the grinding/polishing zones is referred to as the face side of thegrinding/polishing sheet.

According to the invention a sample is only treated on onegrinding/polishing zone at the time, thereby avoiding grinding/polishingmaterial and waste being transported from one zone to another duringtreatment of a sample.

The diameter of the sheet may preferably be between 200-500 mm, morepreferably between 300-400 mm, however, it will be obvious to theskilled person that the sheet may have any size as long as it ispossible to rotate the sheet on a rotatable disc.

The sheet is preferably made from a base layer or support sheet, havinga substantially plane first surface onto which surface thegrinding/polishing zones are applied. The base layer may in general bemade of any type of materials, which can withstand a grinding/polishingprocess e.g. metal, impregnated woven or non-woven tissue, cardboard,plastic, such as plastic with incorporated glass fibres or metalparticles etc.

The second surface of the base layer is adapted to be applied onto arotatable abutment in a grinding apparatus. For this application, it isnormally required that this second surface of the base layer issubstantially plane.

In order to facilitate a temporary fixation of the cover sheet accordingto the invention to a magnetized movable abutment in a grindingapparatus, it is preferred that the base layer comprises ferromagneticmaterial. The ferromagnetic material according to this embodiment can bein any form and be placed anywhere in the base layer, e.g. in terms offerromagnetic granules incorporated in a polymer liner. However,according to the invention, it is strongly preferred to use a metal foilas base layer, e.g. a foil having a thickness of around 0.05-2 mm.

Alternatively, the cover sheet according to the invention may beprovided with a layer of an adhesive material on its second side i.e.the side to be facing the abutment during use in order to provide thenecessary temporary fixation to said abutment.

The grinding/polishing zones are applied onto the base layer by use ofany suitably means depending on the type of the zone. If the zone is inthe form of a resilient tissue, it is preferred to apply the zone by useof an adhesive e.g. as described in FR 2.226.068. If the zone is in theform of separate segments, it may preferably be applied by use ofadhesive or through a stencil as described in WO 96/07508. If the zoneis in the form of a material having incorporated grains, it maypreferably be applied by using an adhesive in the form of a bindingagent, which may e.g. be applied using a silk printing method asdisclosed in WO 99/08837.

The annular grinding/polishing zones are applied onto the base layerwith a distance from each other to thereby create an annular distancingzone in the form of an annular channel between two juxtaposedgrinding/polishing zones. This means that a grinding/polishing sheethaving 3 annular grinding/polishing zones has 2 annular channels betweenthese grinding/polishing zones and, etc.

It is preferred that each of the annular channels has a depth measuredfrom the lowest point of the channel perpendicular to the face surface,to the plane defined by the upper surface of the grinding/polishing orcleaning zone lying next to the channel and closer to the centre of thesheet than the channel, which is at least 100 μm. Preferably, at leastone, and more preferably all of the channels of the grinding/polishingsheet have a depth of between 0.1 and 3 mm, more preferably between 0.5and 2 mm.

It has surprisingly been found that these channels in general reduce therisk of transferring grains from one zone to another. In particular, ithas been found that these channels when they have depth, which issufficiently deeper than the average grain size of the grinding grains,which is used during the grinding process, prevent the grains frompassing from a first grinding/polishing zone to a secondgrinding/polishing zone, which is closer to the centre of thegrinding/polishing sheet. Thereby, it is possibly to preparemetallographic preparations without any unwanted grain marks on thepreparations.

The width of a channel measured as its radial extends should preferablybe at least 1 mm, more preferably between 2 and 20 mm, and even morepreferably between 4 and 10 mm. In situations where thegrinding/polishing sheet contains 2 or more annular channels, the widthof the respective channels may vary from each other. However, it ispreferred that the width of the annular channels is substantially equalto each other.

The grinding/polishing sheet may preferably comprise between 2 and 6annular grinding/polishing zones, more preferably 2, 3 or 4 annulargrinding/polishing zones. Each of the annular grinding/polishing zoneshas a grinding or polishing surface in the form of a hard or resilientsurface acting as a substrate for a grinding and/or polishing agent orin the form of a surface containing abrasive grains.

The width of the grinding/polishing zones measured as the radialextension of the zones may vary from each other or they may preferablybe substantially equal to each other. Preferably, the zones have anequal width of between 10 and 100 mm, more preferably between 15 and 50mm and even more preferably, between 20 and 35 mm.

In one embodiment it is preferred that a sample to be prepared has adiameter, which is larger than the width of any of thegrinding/polishing zones. The entire width of the grinding/polishingzone will then be in contact with the sample to be grinded/polished.Consequently the zones will be applied with a uniform wear. When thediameter of the sample to be treated is larger than any of thegrinding/polishing zones the waste material e.g. dirty fluid from theprocess are easier transported into the channels and away from thegrinding/polishing zones.

In an alternative embodiment the diameter of the sample to be treated issmaller than the width of the grinding/polishing zones. In order toinduce a uniform wear on the grinding/polishing zones in this embodimentthe sample is swept side to side all over the surface of thegrinding/polishing surface. The sweeping will also facilitate thetransport of waste material away from the grinding/polishing zones andinto the channels between the zones.

The diameter of the sample is normally to be considered the diameter ofa circle, as the cross section of the sample to be treated in most casesare circular. The circular cross section area of the sample is incontact with the grinding/polishing zones. If the cross section of thesample is not circular, the diameter is defined as the diameter of acircle having the same cross section area as the sample.

One or more of the grinding/polishing zones may be provided with one ormore e.g. 4 transverse channels extending substantially in radialdirection across the zones, and e.g. having a width from 1 to 10 mm. Thetransverse channels may have a depth of between 0.1 and 3 mm, morepreferably between 0.5 and 2 mm. These transverse channels in thegrinding/polishing zones serve to drain off dirty fluid from the zonesinto the annular channels or away from the sheet.

In a preferred embodiment, the grinding/polishing sheet furthercomprises one or more cleaning zones, preferably in the form of a zonehaving a resilient surface, e.g. provided by applying a zone-shapedtextile onto the face side of the sheet. The zone shaped textile maye.g. be in the form of a nappy, bristly or brushed textile material. Thezone shaped textile may also be provided with one or more transverseextending substantially in radial direction across the zones, and e.g.having a width from 1 to 10 mm. These transverse channels in the zoneshaped textile serve to drain off dirty fluid from the cleaning zone.

The cleaning zones may have a width as described above for thegrinding/polishing zones.

In a preferred embodiment the grinding/polishing sheet comprises onecleaning zone, which preferably is at the periphery of thegrinding/polishing sheet.

In the following, the innermost grinding/polishing zone is designated,the in radial direction innermost annular grinding/polishing zone; theoutermost grinding/polishing zone is designated, the in radial directionoutermost annular grinding/polishing zone, or the firstgrinding/polishing zone. The grinding/polishing zones further, beingnumbered from the outermost annular grinding/polishing zone to theinnermost annular grinding/polishing zone as the firstgrinding/polishing zone, the second grinding/polishing, and etc.

As it will be clear to the skilled person, the grinding/polishing sheetaccording to the invention may be designed to be used in one or more orall of the grinding/polishing steps plane grinding steps, one or morefine grinding steps, and one or more polishing and optionally oxidepolishing steps.

In a preferred embodiment of the grinding/polishing sheet according tothe invention, the in radial direction outermost annulargrinding/polishing zone is a grinding zone, by use of which a planegrinding step can be performed, said outermost zone preferably comprisesa grinding surface in the form of a surface layer having incorporatedabrasive particles e.g. as described in WO 99/08837 or in the form of asubstrate for a grinding agent e.g. as described in WO 96/07508. Thisembodiment may preferably comprise 2 or 3 annular grinding/polishingzones, and furthermore, the in radial direction innermost zone maypreferably be a grinding zone by use of which a fine grinding step canbe performed. This innermost zone may comprise a grinding surface in theform of a surface layer having incorporated abrasive particles e.g. asdescribed in WO 99/08837 or in the form of a substrate for a grindingagent e.g. as described in WO 96/07508.

Alternatively, the innermost zone in this embodiment may be a polishingzone by use of which a polishing step can be performed. This innermostzone may preferably comprise a polishing surface in the form of asurface layer constituting a substrate for a polishing agent. Suchsurface layers are generally known in the art, and may e.g. be in theform of a woven or non-woven textile e.g. impregnated with bakelite orsimilar polymeric materials. Preferably, the polishing surfaces may beconstituted by the surface of a textile selected from the groupconsisting of canvas, linen, velvet and velvety textiles. The textilemay e.g. be adhered by use of an adhesive such as hot melt, twocomponent adhesives or solvent based adhesives to the base of the sheet.

In this embodiment wherein the in radial direction outermost annulargrinding/polishing zone is a grinding zone, and the in radial directioninnermost grinding/polishing zone is a polishing zone, thegrinding/polishing sheet should preferably comprise at least 4grinding/polishing zones. In this embodiment, it is further preferredthat the outermost annular grinding/polishing zone is a grinding zonefor used in the performance of a plane grinding step, that the secondoutermost annular grinding/polishing zone is a grinding zone for use inthe performance of a fine grinding step, and that the third and fourthoutermost annular grinding/polishing zone are polishing zones.

In another preferred embodiment, the grinding/polishing sheet preferablycomprises 2 or 3 grinding/polishing zones and preferably the in radialdirection outermost annular zone being a polishing zone by use of whicha polishing step can be performed. The outermost zone preferablycomprising a polishing surface as described above. In this embodiment,it is furthermore preferred that the remaining zone or zones also arepolishing zones, wherein the in radial direction innermost zone is apolishing zone by use of which an oxide polishing step can be performed.The innermost zone preferably comprises a polishing surface in the formof a surface layer constituting a substrate for an oxide-polishingagent, as it is well known in the art.

A preferred embodiment of the grinding/polishing sheet according to theinvention the sheet further comprises at least one cleaning zone, and itis preferred that each grinding/polishing zone has an associatedcleaning zone in the form of the nearest annular channel towards thecentre of the grinding zone.

In a particularly preferred embodiment of the grinding/polishing sheetaccording to the invention one or more of the grinding/polishing zonesare releasable attached to the grinding/polishing sheet. The embodimentprovides the possibility to design a grinding/polishing sheet withspecific desired properties and fast and easy to change those propertieson the sheet. Furthermore it is possible to compensate for uneven wearon the different zones. If one zone is worn out and the remaining zonesare still useable it is only necessary to replace the worn out zone andnot the entire grinding/polishing sheet.

The one or more of the grinding/polishing zones may be releasableattached to the grinding polishing sheet by any known methods ofattachment, including use of an adhesive layer, hooks and loops commonlyknown as Velcro), magnetic force, screws, pins, clips, press studs orvacuum.

In one preferred embodiment the grinding/polishing sheet thegrinding/polishing zones has a layer of adhesive applied to the sidefacing the grinding/polishing sheet.

In an alternative preferred embodiment of the grinding/polishing sheetwith releasable grinding/polishing zones a layer of adhesive is appliedto all or a part of the grinding/polishing sheet, preferably theadhesive layer is applied in annular patterns corresponding to theannular grinding/polishing zones.

Preferably the layer of adhesive is coated with a cover lining. Thecover lining protects the layer of adhesive, when it is not used forattachment of grinding/polishing zones to the grinding/polishing sheet.

The invention also relates to a method of preparation of amaterialographic sample or a set of materialographic samples by use ofone or more grinding/polishing sheets according to the invention.

A set of samples includes up to 6 samples, preferably 1 to 3 samplesassembled in a sample holder. The number of samples which can be treatedsimultaneously depends on the size of the samples and the width of theindividually grinding/polishing zones. If the samples are 25, 30 or 40mm, which are traditionally sample sizes, it is preferred to treat onesample at the time.

The method according to the invention may be carried out manually,semi-automatically or automatically and includes the steps of:

-   -   i) applying a grinding/polishing sheet on a rotatable disc,    -   ii) treating the sample(s) by bringing it/them into contact with        the grinding/polishing zones one by one, by starting with the in        radial direction outermost grinding/polishing and terminating        with the in radial direction innermost grinding/polishing zone;        each step of treatment comprises applying a lubricant to the        surface of the grinding/polishing zone and optionally applying a        grinding or polishing agent to the surface of the        grinding/polishing zone;    -   iii) optionally replacing the grinding/polishing sheet on a        rotatable disc, and repeating step ii).

In the first step i), it is preferred to apply a grinding/polishingsheet comprising one or more annular grinding zones for plane grindingthe sample or samples. As described above, these zones may comprise agrinding surface as described above. If the zone is in the form of asubstrate for a grinding agent, such grinding agent is applied onto thesurface of the zone in step ii). Grinding agents are generally known tothe skilled person and may preferably be constituted by a dispersion ofdiamond grains. The grains in the plane grinding step or steps shouldpreferably have an average particle size of between 25 and 100 μm. Ifthere is more than one plane grinding zone, the grains incorporated orapplied in the form of the grinding agent preferably graduate from alager average size in the first plane grinding zone to smaller averagesize in the following second or possible third plane grinding zone.

The first applied grinding/polishing sheet may also comprise one or moregrinding zones for performing a fine grinding. If the sheet does notcontain such zones, the sheet is preferably replaced by another sheetcomprising such zones for fine grinding.

The sample(s) is/are now treated by contacting these one or more annulargrinding zones for fine grinding the sample or samples. As describedabove, these zones may as well comprise a grinding surface in the formof a surface layer having incorporated abrasive particles or in the formof a substrate for a grinding agent. If the zone is in the form of asubstrate for a grinding agent, such a grinding agent is applied ontothe surface of the zone. The grains in the fine grinding step or stepsshould preferably have an average particle size of between 5 and 20 μm.If there is more than one fine grinding zone, the grains incorporated orapplied in the form of the grinding agent preferably graduate from alarger average size in the first fine grinding zone to a smaller averagesize in the following second or possible third fine grinding zones.

The first applied grinding/polishing sheet or optionally replacement forit may also comprise one or more polishing zones for performing apolishing step. If the sheet does not contain such zones, the sheet ispreferably replaced by a sheet comprising such zones for polishing.

The sample(s) is/are now treated by contacting these to one or moreannular polishing zones for polishing the sample or samples. Asdescribed above, these zones may as well comprise a polishing surface inthe form of a substrate for a polishing agent e.g. a tissue layer. Apolishing agent e.g. in the form of a suspension of diamond grains, isapplied onto the surface of the zone in step ii). The grains in thepolishing step or steps should preferably have an average particle sizeof 1-4 μm. If there is more than one polishing zone, the grains appliedin the form of the polishing agent preferably graduate from a largeraverage size in the first polishing zone, to a smaller average size inthe following second or possible third polishing zones.

The first applied grinding/polishing sheet or optionally replacement forit may also comprise one or more oxide polishing zones for performing anoxide-polishing step. If the sheet does not contain such zones, thesheet may be replaced by a sheet comprising such zones for oxidepolishing.

The sample(s) is/are now treated by contacting these to one or moreannular oxide-polishing zones for polishing the sample or samples. Asdescribed above, these zones may as well comprise an oxide-polishingsurface in the form of a substrate for an oxide-polishing agent e.g. atextile layer. An oxide-polishing agent e.g. in the form of an aqueoussuspension of SiO₂ and/or Al₂O₃ is applied onto the surface of the zonein step ii).

It should be observed that in all the treatment steps ii) a lubricant isapplied. Such lubricants are generally known to the skilled person, andmay e.g. consist of water and/or ethanol. If the grinding or polishingagent contains water or ethanol this agent may also constitute thelubricant.

It is generally preferred that the sample(s) is/are cleaned between thepolishing steps, and preferably also between the grinding steps andpolishing steps. This cleaning may be conducted by use of water and/orethanol preferably by bringing the sample(s) in contact with a textilee.g. a rotatable disk covered with a textile onto which water and/orethanol are added. The sample(s) is/are slightly pressed against thetextile preferably during the continuously addition of water/ethanol.The sample(s) may preferably be cleaned by bringing them into contactwith a cleaning zone as described above during the addition ofwater/ethanol. The cleaning of the grinding/polishing sheet may also beperformed by exposing the grinding/polishing sheet to ultrasoniccleaning.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, a number of preferred embodiment will be describedwith references to the drawings where:

FIG. 1 shows the surface of a grinding/polishing sheet according to theinvention,

FIG. 2 shows an embodiment of the grinding/polishing sheet according tothe invention with radial channels,

FIG. 3 shows an embodiment with alternative shape of radial channels,

FIG. 4 shows an embodiment with releasable attached grinding/polishingzones,

FIG. 5 shows an alternative embodiment with releasable attachedgrinding/polishing zones,

FIG. 6 shows a grinding/polishing sheet according to the invention withcleaning zones,

FIG. 7 shows an embodiment of the grinding/polishing sheet according tothe invention,

FIG. 8 shows a grinding/polishing sheet according to the invention witha sample, and

FIG. 9 shows a preferred embodiment of the grinding/polishing sheetaccording to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The grinding/polishing sheet seen from above in FIG. 1 a has 5grinding/polishing zones 1, 2, 3, 4, 5 and channels 6 between all of thezones. In FIGS. 1 b and 1 c the sheet is seen along the line FF′. InFIG. 1 b all the grinding/polishing zones have the same height over thegrinding/polishing sheet 7. In the embodiment shown in FIG. 1 c thegrinding/polishing zones have different heights over thegrinding/polishing sheet, and the heights of the grinding/polishingzones increases towards the centre of the grinding/polishing sheet. Forsome purposes the embodiment of FIG. 1 c has the advantage that itprevents the transport of grinding/polishing material and waste from onegrinding/polishing zone to another more efficiently than embodimentswith the zones in the same heights over the grinding/polishing sheet.

In FIG. 2 and FIG. 3 embodiments with radial channels are seen. Thesheets comprise grinding/polishing and/or cleaning zones 1, 2, 3, 4, 5and annular channels 6 and furthermore radial channels 8.

FIG. 4 a shows a grinding/polishing sheet according to the inventionwith grinding/polishing zones 1, 2 having a channel 6 in between. In thecentral part of the sheet 9 the grinding/polishing zones can bereleasable attached. FIG. 4 b shows the sheet along the line FF′. Thegrinding/polishing zones are attached to the sheet 7.

FIG. 5 a shows an embodiment with grinding/polishing zones 1 and 2 witha channel 6 in between, where one or more zones can be releasableattached in the central area 10 on the sheet. The area 10 has agranulated surface in order to facilitate the release of attached zones.FIG. 5 b shows the sheet along the line FF′.

In FIG. 6 a is seen a grinding/polishing sheet with grinding/polishingzones 1, 2, 3 and cleaning zones 11. The sheet of FIG. 6 a is shownalong the line FF′ in FIG. 6 b.

FIG. 7 a and 7 b shows an alternative embodiment of thegrinding/polishing sheet according to the invention. Thegrinding/polishing sheet has grinding/polishing zones 1, 2, 3, 4 and 5with channels 6 in between. The grinding/polishing zones 1, 2, 3, 4 and5 have different widths. In the embodiment the width of thegrinding/polishing zones increases towards the centre of the sheet e.g.to compensate for uneven wear on the zones.

FIGS. 8 a and 8 b shows a grinding/polishing sheet according to theinvention with grinding/polishing zones 1, 2, 3, 4 and 5 with channels 6in between. The zones are attached to the sheet 7. On thegrinding/polishing zone 3 a sample is 12 is placed. The sample 12 has adiameter, which is slightly smaller than the width of thegrinding/polishing zone 3. Preferable the sample 12 is swept side toside (parallel to line FF′) on the grinding/polishing zone in order toinduce even wear on the grinding/polishing zone 3.

FIG. 9 shows a preferred embodiment of the grinding/polishing sheetaccording to the invention. The sheet comprises grinding/polishing zones1, 2, 3, 4, 5 and channels 6 in between. A least a part of thegrinding/polishing zones 1, 2 comprise a pattern.

As described above, the number of grinding/polishing zones may vary andfurthermore, the cleaning zone is not essential. Since thegrinding/polishing process preferably should be provided by startinggrinding or polishing at the outermost grinding/polishing zone, followedby the second outermost grinding/polishing zone, the grain sizeincorporated to the zones or added thereto should gradually be reducedfrom the outermost zone to the innermost zone.

Particular preferred embodiments are described in the following:

-   A: A grinding/polishing sheet comprising 4 grinding/polishing zones,    the first zone adapted for performing a plane grinding, and    preferably comprising epoxy incorporated dimond/SiC grains having an    average grain size between 60 and 80 μm. The second zone is adapted    for performing a fine grinding, and preferably comprises epoxy    incorporated diamond/SiC grains having an average grain size between    5 and 20 μm. The third zone is adapted for performing a polishing,    and preferably comprises a textile whereto diamond grains of an    average size between 2 and 4 μm is added prior to or during the    polishing. The fourth zone is adapted for performing an oxide    polishing, and preferably comprises a textile whereto oxide    polishing agent is added prior to or during the oxide polishing.-   B: The grinding/polishing sheet B is a variation of the    grinding/polishing sheet A, wherein one or both of the grinding    zones is replaced with composite material as described in WO    96/07508.-   C: The grinding/polishing sheet C is a variation of the    grinding/polishing sheet A or sheet B, further comprising a cleaning    zone as the outermost zone on the sheet, adjacent to the first    grinding zone.-   D: The grinding/polishing sheet D is a variation of the    grinding/polishing sheet A, B or sheet C further comprising one, two    or three more grinding and/or polishing zones.-   E: A grinding sheet comprising 3 to 6 grinding zones each comprising    epoxy incorporated diamond/SiC grains, which in the outermost or    first zone has an average grain size between 60 and 80 μm, and in    the following zones having grains, which gradually decrease, towards    the innermost zone.-   F: The grinding sheet F is a variation of the grinding sheet E,    wherein one or more of the grinding zones are replaced with    composite material as described in WO 96/07508.-   G: A polishing sheet comprising 2 to 6 polishing zones, each    comprising a textile whereto diamond grains of an average size    between 1 and 5 μm is added prior to or during the polishing. The    grain size of the diamond gradually decreases from the outermost    zone to the innermost zone.-   H: The grinding sheet H is a variation of the grinding sheet G,    wherein the innermost zone is replaced by an oxide polishing zone    whereto oxide polishing agent is added prior to or during the oxide    polishing.-   I: The grinding/polishing sheet I is a variation of the sheets A, B,    C, D, E, F, G or H, in which one or more areas on the sheet    comprises a surface for temporary or releasable fixation of one or    more self-sticking annular abrasive or polishing zones. The    self-sticking annular zones may be changed to compensate for wear    and thereby increase the lifetime of sheet I. Furthermore, the    self-sticking annular zones may be changed to optimise the    combination of grinding/polishing media for specific types of    samples thereby making the sheet more flexible towards the type of    sample.-   J: The grinding/polishing sheet J is a variation of the sheets A, B,    C, D, E, F, G or H in which one or more of the grinding/polishing    zones sheet comprises an adhesive surface for temporary or    releasable fixation of the annular abrasive or polishing zone. The    annular grinding or polishing zones may be changed to compensate for    wear thereby increasing the lifetime of sheet J. Furthermore, the    annular zones may be changed to optimise the combination of    grinding/polishing media for specific types of samples thereby    making the sheet more flexible towards the type of sample.

1. A treating sheet for preparation of a materialographic sample or aset of materialographic samples, said sheet being substantially circularand having a back side and a face side, said face side comprising atleast two annular treating zones, between said at least two treatingzones said face side comprises intermediate annular distancing zones,each of said treating zones having a grinding or polishing surface, eachdistancing zone creating an annular channel between juxtaposed treatingzones, wherein the entire radial width of each of said treating zonesprovides a contact surface, said treating zones have a width between 10and 100 mm and wherein at least one of the annular channels between saidtreating zones has a depth measured from a lowest point of the channelto a plane defined by an upper surface of an adjacent treating zone, theadjacent treating zone lying next to the channel and closer to thecenter of the sheet than the channel between 0.1 and 3 mm.
 2. A treatingsheet according to claim 1, wherein said face side comprises between 2and 6 annular treating zones.
 3. A treating sheet according to claim 2,wherein said face side further comprises one or more cleaning zones. 4.A treating sheet according to claim 1, wherein at least one of thetreating zones comprises at least one non-continuous area.
 5. A treatingsheet according to claim 4, wherein the at least one non-continuous areacomprises discrete geometrical structures or the at least onenon-continuous area is part of an annular structure forming channels inradial direction.
 6. A treating sheet according to claim 5, wherein saiddiscrete geometrical structures are polygons.
 7. A treating sheetaccording to claim 1, wherein the width of each channel is at least 1mm.
 8. A treating sheet according to claim 7, wherein the width of saidchannels is between 2 and 20 mm.
 9. A treating sheet according to claim1, wherein the widths of the treating zones are substantially equal toeach other.
 10. A treating sheet according to claim 1, wherein at leastone treating zone has a width different from the widths of othertreating zones.
 11. A treating sheet according to claim 1, wherein anoutermost annular treating zone is a grinding zone by use of which aplane grinding step can be performed, said outermost annular treatingzone comprising a grinding surface in the form of a surface layer havingincorporated abrasive particles or in the form of a substrate for agrinding agent.
 12. A treating sheet according to claim 11, wherein saidface side comprises 2-6 annular treating zones, an innermost treatingzone being a grinding zone by use of which a fine grinding step can beperformed, said innermost treating zone comprising a grinding surface inthe form of a surface layer having incorporated abrasive particles or inthe form of a substrate for a grinding agent.
 13. A treating sheetaccording to claim 11, wherein said face side comprises at least 3annular treating zones, an innermost treating zone being a polishingzone by use of which a polishing step can be performed, said innermosttreating zone comprising a polishing surface in the form of a surfacelayer constituting a substrate for a polishing agent.
 14. A treatingsheet according to claim 11, wherein said face side comprises a firstgrinding zone adapted for performing a plane grinding of one or morematerialographic samples, a second grinding zone adapted for performinga fine grinding of at least one materialographic sample, a third zoneadapted for performing a polishing of at least one materialographicsample, and a fourth zone adapted for performing a second polishing ofat least one materialographic sample.
 15. A treating sheet according toclaim 1, wherein said face side comprises 2-6 annular treating zones, anoutermost annular treating zone being a polishing zone by use of which apolishing step can be performed, an outermost zone comprising apolishing surface in the form of a surface layer constituting asubstrate for a polishing agent.
 16. A treating sheet according to claim11, wherein an innermost annular treating zone is a polishing zone byuse of which an oxide polishing step can be performed, said innermostzone comprising a polishing surface in the form of a surface layerconstituting a substrate for an oxide polishing agent.
 17. A treatingsheet according to claim 1, wherein the sheet further comprises at leastone cleaning zone, each treating zone has an associated cleaning zone inthe form of the nearest annular channel towards the center of thegrinding zone.
 18. A treating sheet according to claim 11, wherein atleast one of the treating zones is releasably attached to the treatingsheet.
 19. A treating sheet according to claim 18, wherein at least oneof the treating zones is releasably attached to the treating sheet byuse of an adhesive layer, hooks and loops, magnetic force, screws, pins,clips, press studs or vacuum.
 20. A treating sheet according to claim19, wherein each of the treating zones has a layer of adhesive appliedto a side facing the face side of the treating sheet.
 21. A treatingsheet according to claim 19, wherein a layer of adhesive is applied toall or a part of the face side of the treating sheet.
 22. A treatingsheet according to claim 21, wherein the layer of adhesive is coatedwith a cover lining.
 23. A treating sheet according to claim 1, whereinsaid treating zones have a width of between 15 and 50 mm.
 24. A treatingsheet according to claim 1, wherein the depth of said at least one ofthe annular channels is between 0.5 and 2 mm.
 25. A treating sheetaccording to claim 12, wherein said face side comprises between 2 and 3annular treating zones.
 26. A method of treating a materialographicsample which comprises the steps of: (a) providing a rotatable disc, (b)mounting a treatment sheet on the rotatable disc, said treatment sheethaving an exposed face with an outer annular treatment area, an innerannular treatment area, and an annular channel therebetween, one of saidouter and inner annular treatment areas containing grinding grains of acertain average grain size, (c) rotating said rotatable disc and saidtreatment sheet thereon, (d) applying a lubricant to the face of saidtreatment sheet, (e) contacting a materialographic sample with firstsaid outer annular treatment area and then said inner annular treatmentarea of said treatment sheet such that said materialographic samplecontacts the entirety of both said outer and inner annular areas, and(f) collecting loosening grains of said grinding grains within saidannular channel.
 27. The method according to claim 26, wherein each ofsaid outer and inner annular treatment areas has a width between 10 and100 mm.
 28. The method according to claim 27, wherein thematerialographic sample respectively extends across the entire width ofthe inner annular treatment area and thereafter across the entire widthof the outer annular treatment area of the outer annular treatment area.29. The method according to claim 27, wherein the materialographicsample, in order to contact the entirety of the outer and inner annularareas, is moved radially outwardly relative to the rotating treatmentsheet.